Dynamic Behavior Of Porous Metal Sandwich Plates For Ship Under Ice-impact Load

With the development of the Arctic waterway and exploration of the polar resources,the anti-ice performance of ship structures have attracted more and more attention.Porous metal sandwich structure has excellent mechanical properties.It is widely used in lightweight structure and collision impact protection.Based on the experimental and numerical methods,the dynamic responses of aluminum foam sandwich plates(AFSP)under ice-impact load are studied,and the differences of dynamic responses of AFSP under ice impact and rigid mass impact are compared and analyzed.Meanwhile the effect of ice fragmentation on the energy absorption of AFSP is illustrated,and the effects of collision kinetic energy and impact momentum on the dynamic responses and energy absorption of AFSP are revealed.The main contents of this thesis are as follows:(1)The quasi-static compression tests of aluminum foam and the quasi-static tensile tests of aluminum plate were carried out by universal testing machine,and the quasi-static mechanical properties were obtained.The material tests of ice were performed and the quasi-static mechanical properties of ice were obtained.The samples of ice were prepared and quasi-static compression of cylindrical ice at different heights was carried out.The experimental results show that there is a long stress platform in the compressive stress-strain curve of aluminum foam core,which can withstand large plastic deformation.The compressive strength of fresh water ice is weak.Under the condition of a certain cross-section area,the peak compressive strength of ice specimens increases as the height of the cylindrical ice increases.(2)The preparation process of AFSP and wedge ice was introduced,and the AFSP-wedge ice and equivalent steel plate-wedge ice collision experiment were carried out by horizontal impact machine.The deformation,collision velocity,acceleration and wedge ice were measured.The deformation of AFSP and equivalent steel and the fracture of ice bodies were compared and analyzed.The analysis results show that the anti-ice performance of AFSP is better than that of the hull steel plate.(3)The nonlinear finite element model is established to analyze the dynamic behavior of AFSP under wedge ice impact.The numerical results are compared with those of experiment to verify the reliability of the ice material model and the numerical simulation.On this basis,the dynamic responses of AFSP under ice impact and rigid mass impact are compared,and the effect of ice fragmentation on the energy absorption of AFSP are discussed.The results show that the deformation mode,deformation size and collision force of AFSP are different under ice collision and rigid body collision;ice body crushing affects the size and proportion of energy absorbed by each component of AFSP;ice body crushing will dissipate most of the collision energy,so that the AFSP absorbs less energy and smaller plastic deformation is formed.(4)The nonlinear finite element software ANSYS/LS-DYNA is used to investigate the effects of parameters on the dynamic response of AFSP under wedge ice collision.The effects of collision kinetic energy and impact momentum on the dynamic responses and energy absorption of AFSP are analyzed.The results show that the deformation of AFSP under ice impact load mainly depends on the collision kinetic energy;the fixed impact momentum,the energy absorption ratio of the aluminum foam core layer increases with the increase of the collision kinetic energy;the fixed collision kinetic energy,the energy absorption ratio of the aluminum foam core layer decreases as the collision momentum increases.